1. Field of the Invention
The present invention relates to a particulate composition containing anhydrous crystalline 2-O-α-D-glucosyl-L-ascorbic acid, process for producing the same, and uses thereof, more particularly, to a hardly solidifiable particulate composition containing anhydrous crystalline 2-O-α-D-glucosyl-L-ascorbic acid, process for producing the same, and uses thereof as a material for food products, cosmetics, quasi-drugs, and pharmaceuticals.
2. Description of the Prior Art
Due to its advantageous physiological activities and antioxidant action, L-ascorbic acid has been used for various purposes, including those for food products and cosmetics. L-Ascorbic acid, however, is unstable because of its direct reducibility, and it is susceptible to receive oxidative degradation and to lose its physiological activity as the crucial defect. To overcome the defect, the present applicant, as one of the co-applicants of Patent Literature 1, disclosed 2-O-α-D-glucosyl-L-ascorbic acid that is composed of one molecule of D-glucose bound to the hydroxyl group at the C-2 position of L-ascorbic acid (hereinafter, abbreviated as “ascorbic acid 2-glucoside”, throughout the specification). As outstanding characteristics, ascorbic acid 2-glucoside does not exhibit direct reducibility but has a satisfactory stability, and it exerts the physiological activities inherent to L-ascorbic acid after being decomposed in living bodies into L-ascorbic acid and D-glucose by an in vivo enzyme inherently existing in the living bodies. According to the process disclosed in Patent Literature 1, ascorbic acid 2-glucoside is formed by allowing a saccharide-transferring enzyme such as cyclomaltodextrin glucanotransferase (abbreviated as “CGTase”, hereinafter) or α-glucosidase to act on a solution containing L-ascorbic acid and α-glucosyl saccharide compound.
In Patent Literature 2, the present applicant succeeded in crystallizing ascorbic acid 2-glucoside from a saturated solution of ascorbic acid 2-glucoside and disclosed crystalline ascorbic acid 2-glucoside and a particulate composition containing the same. Until now, crystalline ascorbic acid 2-glucoside has been known to merely exist in an anhydrous crystalline form. Non-Patent Literatures 1 and 2 reported data on X-ray structure analysis for crystalline ascorbic acid 2-glucoside.
In Patent Literatures 3 and 4, the same applicant as the present invention disclosed a process for collecting a high ascorbic acid 2-glucoside content fraction, comprising subjecting a solution containing ascorbic acid 2-glucoside formed by an enzymatic reaction to column chromatography using a strong-acid cation exchange resin, and collecting the fraction. In Patent Literature 5, the same applicant disclosed a process for producing a high ascorbic acid 2-glucoside content product, comprising subjecting a solution containing ascorbic acid 2-glucoside formed by an enzymatic reaction to electrodialysis using an anion-exchange membrane to remove impurities such as L-ascorbic acid and saccharides from the solution; and in Patent Literature 6, the same applicant disclosed a process for producing a high ascorbic acid 2-glucoside content product, comprising subjecting a solution containing ascorbic acid 2-glucoside to an anion-exchange resin and selectively desorbing the ingredients adsorbed on the resin to obtain a fraction rich in ascorbic acid 2-glucoside.
In Patent Literature 7, the same applicant as the present invention disclosed a process for producing ascorbic acid 2-glucoside, comprising allowing α-isomaltosyl glucosaccharide-forming enzyme or α-isomaltosyl glucosaccharide-forming enzyme in combination with CGTase to act on a solution containing L-ascorbic acid and α-glucosyl saccharide compound to form ascorbic acid 2-glucoside. Patent Literatures 8 and 9 applied for by the same applicant as the present invention disclose that α-isomaltosyl glucosaccharide-forming enzyme and α-isomaltosyl-transferring enzyme catalyze saccharide transferring to L-ascorbic acid to form ascorbic acid 2-glucoside.
Referring to uses of ascorbic acid 2-glucoside, many proposals have been made as shown in, for example, Patent Literatures 10 to 29. Depending on its advantageous characteristics, ascorbic acid 2-glucoside has been conventionally used as a material for food products, cosmetics, quasi-drugs, or pharmaceuticals; and it has been extensively used in other uses where L-ascorbic acid could not be used due to its instability, to say nothing of conventional uses of L-ascorbic acid.
As described above, ascorbic acid 2-glucoside is now known to be produced by using L-ascorbic acid and amylaceous substances as materials and various saccharide-transferring enzymes. According to the findings already obtained by the present applicant so far, the method for allowing CGTase as a saccharide-transferring enzyme to act on a solution containing L-ascorbic acid and amylaceous substance is an industrially advantageous method because of its highest production yield of ascorbic acid 2-glucoside. Based on this finding, the present applicant has been producing particulate compositions containing anhydrous crystalline ascorbic acid 2-glucoside by the method of allowing CGTase to act on a solution containing L-ascorbic acid and amylaceous substance, and commercializing the particulate compositions as materials for cosmetics/quasi-drugs and for food products, which are respectively commercialized as “AA2G” and “ASCOFRESH”, product names of such particulate compositions and commercialized by Hayashibara Biochemical Laboratories, Inc., Okayama, Japan, and Hayashibara Shoji Inc., Okayama, Japan, respectively (these conventional particulate compositions containing anhydrous crystalline ascorbic acid 2-glucoside that have been commercialized as materials for cosmetics/quasi-drugs and for food products are abbreviated as “quasi-drug grade powders”, hereinafter.)
Although quasi-drug-grade powders have, as a quality standard, a relatively high purity as high as 98.0% by weight or higher in terms of the purity of ascorbic acid 2-glucoside and retain a satisfactory free-flowing ability as a powder (throughout the specification, “powder(s)” means “particulate composition(s)”, unless specified otherwise”) just after production, they have the defect that they may solidify due to their dead load or moisture absorbency, when allowed to stand under a relatively high temperature and humid conditions for a relatively long period of time. Considering such defect, conventional quasi-drug-grade powders have been commercialized being packed in polyethylene bags by 10 kg aliquots thereof and placed, along with desiccants, in steel cans with covers. Even with the form of such product form, quasi-drug-grade powders, however, still have the problem that they may occasionally solidify and lose their usefulness as powders, when stored for a relatively long period of time. Solidification of particulate compositions, which contain anhydrous crystalline ascorbic acid 2-glucoside to be used as a material for cosmetics, quasi-drugs, or food products, may usually cause troublesome event in the steps of, for example, transporting, sieving, or mixing materials, when a production plant is designed on the premises that materials with satisfactory free-flowing ability will be used.